The invention relates to a system for a machine having a large number of proximity sensors, as well as to a proximity sensor, and a primary winding for this purpose. The invention can be used for supplying electrical power to proximity sensors that are mounted on moving machine components (e.g. industrial robots, automatic production machines, and automated production machines).
A decentralized supply for a large number of transmitters utilizing inductive power transmission is known from Schoener J et al.: xe2x80x9cDezentrale Versorgung aktiver Geberxe2x80x9d [Decentralized supply of active transmitters], Radio Fernsehen Elektronik, DE, VEB Verlag Technik, Berlin, Volume 41, No. 9, Sep. 1, 1992 (1992-09-01), pages 627-630, in conjunction with a system for position detection. A constant-frequency alternator that is installed on a crane operates at a fixed frequency of 100 to 130 kHz or more acting on a frame antenna that is tuned to resonance and transmits AC power to the compact assemblies installed in the transmitters, and which are likewise equipped with a frame antenna tuned to resonance. The induced voltage is rectified and feeds the compact assembly. The distance to be bridged is 150 mm. A power level of approximately 100 mW must be transmitted for one compact assembly.
German published, non-prosecuted patent application DE 44 42 677 A1 discloses a method and a configuration for supplying an electrical load with an electrical supply voltage or an electrical supply current. The configuration supplies the voltage or current via radio waves from a radio transmitter to a radio receiver that is electrically connected to the load. The radio receiver converts the radio waves to the electrical supply voltage or the electrical supply current. The radio waves can come from the electromagnetic high frequency range (radio waves) or also from the microwave range. The electrical loads can be, for example, power or voltage sensors.
It is accordingly an object of the invention to provide a system for a machine having a large number of proximity sensors, as well as a proximity sensor, and a primary winding for this purpose that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that specifies a cost-effective and reliable system for a machine having a large number of proximity sensors, which ensures that electrical power can be supplied to the proximity sensors without using wires. Furthermore, a proximity sensor that is suitable for this purpose will be proposed. In addition, a primary winding that is suitable for this purpose will be proposed.
With regard to the system, the object is achieved by a system for a machine, in particular an automated production machine, having a large number of proximity sensors. Each proximity sensor has at least one secondary winding that is suitable for drawing power from a medium-frequency magnetic field, with at least one primary winding that is fed from a medium-frequency oscillator being provided for supplying the proximity sensors with electrical power without using wires. Each proximity sensor is equipped with a transmitting device that emits radio signals, which contain sensor information of interest, to a central receiving device that is connected to a process computer for the machine.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a system for a machine. The system includes a proximity sensor generating sensor information. A transmitting device transmits the sensor information from the proximity sensor and emitting radio signals containing the sensor information to a central receiving device connected to a process computer for the machine. A secondary winding connects to the proximity sensor for drawing power from a medium-frequency magnetic field. A primary winding is fed from a medium-frequency oscillator. The primary winding is provided for supplying the proximity sensor with electrical power without requiring wires.
With the objects of the invention in view, there is also provided a primary winding including a connection element and a plurality of parallel conductors. The plurality of parallel conductors forms a plurality of separate winding sections, the plurality of separate winding sections are mechanically and electrically connected to one another via the connection element.
With the objects of the invention in view, there is also provided a primary winding. The primary winding includes a number of parallel conductors forming a flexible cable with two cable ends being offset with respect to one another. A connection element electrically and mechanically connecting the two cable ends to one another. Connection lines are connected to the cable ends via the connection element and forming two free winding ends.
With regard to the proximity sensor, the object is achieved by a proximity sensor having a number of secondary windings that are suitable for drawing power from a medium-frequency magnetic field.
The medium-frequency oscillations that are of interest in this context are understood to be those in the range from about 15 kHz to about 15 MHz.
With regard to the primary winding, the object is achieved by a primary winding including a number of separate winding sections. Each of the winding sections is formed from a number of parallel conductors. The individual winding sections are mechanically and electrically connected to one another via connection elements. If one connection element electrically connects two winding sections to one another, the two winding sections are offset with respect to one another, thus forming two free winding ends that are suitable for connection of connection lines to a generator or oscillator.
An alternative embodiment of the primary winding achieves the object by including a primary winding having a flexible cable formed from a number of parallel conductors and a connection element that electrically and mechanically connects the two cable ends to one another. The parallel conductors are offset with respect to one another. Thus, two free winding ends are formed that are suitable for connection of connection lines to a generator or oscillator.
The invention achieves the following advantages. Compared to conventional solutions with a cable connection for supplying electrical power to the proximity sensors, the invention avoids the relatively high cost factor resulting from planning, material, installation, documentation, and maintenance, for a cable connection. In addition, no failures can occur due to cable breaks or poor contacts, for example corroded contacts.
Compared to batteries for supplying power to proximity sensors, no maintenance effort or cost is lost for replacing the batteries. Sometimes, the costs are exacerbated when the batteries are in poorly accessible locations.
In the stated medium-frequency range (from about 15 kHz to about 15 MHz), the disadvantages that result from skin effects, for example the losses that occur, are still manageable. No electromagnetic waves are emitted, because the primary windings are too small in comparison to the wavelengths that occur. Therefore, the primary windings do not act as antennas. This allows the configurations to be constructed in a simple manner. There is no need to conduct EMC measurements on any radiated interference. A further advantageous factor is that medium-frequency magnetic fields are shielded only to a minor extent by metallic machine components so that a magnetic field that is sufficiently powerful to supply power is advantageously produced even at inaccessible points in a machine.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a system for a machine having a large number of proximity sensors, as well as a proximity sensor, and a primary winding for this purpose, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.